The present invention relates to a tunnel excavator having a body provided with a horizontally and vertically swingable excavating portion, a gathering portion for gathering materials excavated by the excavating portion, and a transporting portion for transporting the gathered materials rearwardly of the body for discharging the same.
Heretofore, the excavating portion of a conventional excavator of the type described above comprises a rotating cutter. When the condition of the ground to be excavated varies, the only measure for accommodating the variation in the condition of the ground is to interchange the cutter with one having a different configuration and/or different material. Therefore, when a firmly conglomerated ground including solid pebbles or a rock bed having a compressive strength greater than 1000 kg/cm.sup.2 is to be excavated, cemented carbide tips at the forward end of the cutter tends to be broken or detached from the cutter thereby shortening the life of the cutter, while greatly reducing the efficiency of excavation. In other words, it is hardly possible to excavate the firmly conglomerated ground including pebbles or a rock bed having the compressive strength greater than 1000 kg/cm.sup.2 by using a rotating cutter heretofore used in the excavation.
The present invention aims at avoiding the above described disadvantages of the prior art excavator.